After considering the $$$ 5 ch Alpine/JL audio amps, I took a chance on a Crunch amp, that delivers 4x175w. That will be just right to drive the Infinity 6.5 Kappas I bought, plus these woofers. I was really pleased with the classic design and wide range of configuration options and adjustments. This amp totally blew away the ancient Yamaha that pulled out of my basement, and had a faulty channel to boot... I can't wait to see how this sounds after I finish up the door install.
I had considered using the head unit amp of the new Kenwood I'll be buying (I'm sold on the iDataLink Maestro & Dash kit, great quality and looks factory) to power the leftover JLs still in the rear deck. However the high back Recaros really block sound coming from the rear, so I'll do what most shops recommend, and install my own powered sub. I'll get more than enough highs from the component speakers up front, so adding more non directional bass from the trunk is my best option.